Conveyors used in dishwashing machines and dish collection and distribution systems are either a continuously running type, such as disclosed in U.S. Pat. No. 3,237,755, or a continually running type with a manual or automatic stop motion mechanism which stops the conveyor when an article being carried is obstructed. Most conveyors are adapted to travel in a straight line and their connecting links are capable of movement in a vertical plane. Conveyors are also available which turn in a horizontal plane, and their links are pinned and turn about a vertical axis.
Further, conveyors are available in which their links are pinned for movement in both horizontal and vertical planes. These conveyors are supported by a conveyor pan. When trays are placed on the conveyor the bottom of the conveyor or knuckle chain engages the conveyor pan resulting in sliding friction and a wear pattern. To overcome this problem, wear strips are placed in the conveyor pan. Also, the trays being carried, if obstructed, will tend to pile one on top of the other.
The present invention is directed to a conveyor chain adapted to turn in both horizontal and vertical planes, which chain eliminates sliding friction between the chain and the conveyor pan. The conveyor chain also employs a limited upper surface which carries trays but avoids piling one on top of the other in the event a tray is obstructed.
In a preferred embodiment of my invention, a conveyor chain is comprised of a plurality of links, each link engaged to the next link such that there is both oscillatory motion between links about a vertical axis and pivotal movement in a vertical plane about a horizontal axis which passes through the vertical axis.
In the preferred embodiment of the invention, a plurality of links form an endless conveyor chain. The chain is driven in a vertical plane by sprockets. Each link comprises a collar and a yoke joined by a web. The yoke receives the collar of the next link and a sleeve is received within the collar. The vertical axis about which the links oscillate is coincident with the sleeve axis. A roller is secured in the sleeve to provide rolling friction between the chain and a supporting conveyor pan. The sleeve is characterized by a reduced upper surface which surface is adapted to carry the trays but allows the chain to continue running in the event the trays or other articles are obstructed. More specifically, the sleeve includes a dome-shaped or arcuate upper surface which engages with a sliding friction the trays to be carried. The links are pinned together to form an endless chain. The pins serve as shafts for the rollers, and the horizontal axis about which the links pivot is coincident with the axis of the pin.